Extract MP3 Audio from MKV

About MKV and MP3

MKV is the Matroska container — a flexible box that can hold nearly any codec. OBS and most screen recorders write it by default.

MP3 is the most widely supported audio format there is — every browser, player, car stereo and podcast app reads it. It is lossy, so quality is traded for file size, but at 192 kbps and up most listeners cannot tell.

Extracting audio from MKV re-encodes only the audio track — the video is discarded, so even long files finish quickly.

How the conversion works

This tool runs FFmpeg — the same engine behind most media software — compiled to WebAssembly, entirely in the browser. The file is read locally, converted locally and saved straight from memory; nothing is ever uploaded, which also means no queues and no server-side file size limits.

The converter itself is a one-time ~31 MB download on the first conversion, cached by the browser afterwards. Once it is loaded, everything works offline.